Pleural Mesothelioma: Mesothelioma of the Pleura

Pleural mesothelioma is a disease that affects the lining of the lungs, or lung pleura. Sometimes doctors refer to this disease as mesothelioma of the pleura. It is a common misconception that mesothelioma is a type of primary lung cancer; it is not. Mesothelioma is a cancer of the serous membranes. These membranes enclose a number of organs throughout the midsection of the body, including the lungs. The most common type of mesothelioma is one that affects the serous membranes of the lungs: pleural mesothelioma.

Mesothelioma can also affect the serous membranes surrounding the abdomen, called peritoneal mesothelioma, and the membranes surrounding the heart, or pericardial mesothelioma. When mesothelioma spreads to the lungs from the serous linings of the lungs, abdomen or heart, it is considered secondary lung cancer. Also, pleural mesothelioma is sometimes referred to as an asbestos lung cancer. Technically, this is also incorrect, since it does not originate in the lungs. Asbestosis is a type of asbestos lung disease that does originate in the lungs and is often confused with mesothelioma.

Pleural Mesothelioma Cancer

Pleural mesothelioma cancer represents about 75% of all mesothelioma cases. The disease is caused by the inhalation of asbestos fibers that settle in the lungs. These asbestos fibers become inserted in the lung lining (the pleura). Over time, these fibers cause chronic inflammation that eventually leads to growth of cancerous tumors or, in some cases, asbestosis.

Pleural mesothelioma cancer normally appears as multiple tumor masses affecting the parietal surface (inside closer to the lung) and visceral surface (outside further from the lung) of the pleura. Typically the parietal surface has greater involvement than the visceral. The right lung typically shows a slightly higher incidence of mesothelioma, apparently due to the fact that the right lung is larger and has a greater amount of pleural surface area. Also, the lower lungs typically show more tumor masses than the upper lung. This is thought to be due to gravitational factors influencing how the asbestos fibers settle in the lungs after they have been inhaled.

Large growths in the pleura are normally noted in patients upon diagnosis. These growths lead to a complete obliteration of the lung cavity later in the disease. The tumors can spread from the lung pleura to other organs, including the heart and abdomen. This aggressive disease can also invade the lymph nodes and blood system.

Other types of tumors also grow in the pleura, but these are tumors that start in other parts of the body and are not considered pleural mesothelioma. These tumors have metastasized to the pleura. The most common form of non-pleural mesothelioma cancer that occurs is lung cancer, representing about 36% of the cancer occurring in the pleura. The next most common forms are breast cancer (25%), ovarian cancer (5%) and gastric cancer (2%). Lymphoma also accounts for a portion of cancer that has metastasized to the pleura.

Pleural Mesothelioma Symptoms

The most common symptom for pleural mesothelioma patients is chest pain. But, the pain is often not associated directly with the lung pleura and often appears in the shoulder or upper abdomen. Shortness of breath, called dyspnea, is also a symptom. Cough, weight loss and anorexia are present in some patients, but are less common symptoms. The pleural mesothelioma cancer tumors grow quickly and enlarge the pleural space, causing it to fill with fluid. This fluid leads to the discomfort or pain associated with first detection of the disease.

Pleural mesothelioma patients display all three types of mesothelioma cancer cells: epithelioid mesothelioma, sarcomatoid mesothelioma and biphasic mesothelioma.

Pleural Mesothelioma Prognosis

According to a study of 167 patients with proven pleural mesothelioma, the median survival rate of patients following diagnosis was 242 days. The survival rate was also affected by the type of mesothelioma cancer cells; patients with biphasic cell types have the shortest life expectancy.